Digital Camera Zoom Explained

July 1, 2009

If you are looking to buy a digital camera then digital zoom is an essential feature which is often used as a tag line to highlight how good a camera is. The digital zoom is stated in multiples of the number of times the camera is capable to magnify the size of an image such as 3X, 6X or 8X.

Typically digital compact digital cameras are capable of producing more than 4× and ranging up to 15× in SLR camera lenses some advanced digital cameras can deliver up to 24X zoom.

Calculating the Zoom Ratio

All digital cameras have a description of their focal length. Focal length defines the distance from the optical center of the camera’s lens to the camera’s focal point. For a camera without a zoom lens can be said to have its focal length fixed.

On the other hand for a camera with a zoom lens the focal length is variable, which means the position of the lens changes as you zoom in and out.

The focal length of a camera is usually measured in millimeters and as a standard the lower value of the stated focal length such as 35mm, or 28mm is normally the focal length of camera without using the zoom feature. Depending on the zoom lens capability, digital cameras are capable of delivering different outputs such as 85mm, 115mm or 140mm.

In order to calculate the zoom ratio you can divide the two values of the stated focal length(high and low) to get the precise digital zoom capability in any given camera. For example a Canon IXUS 100 IS has the focal lengths of 35mm to 100mm, so we can now divide 100/35=2.8, this tells us the camera has a digital zoom close to 3X.

Written by admin · Filed Under Digital Camera Buying Advice